The US Center for Disease Control (CDC) estimates that more than 1.7 million healthcare associated infections (HAI) are acquired in US hospitals every year, resulting in approximately 100,000 deaths and adding $30-40 billion of direct treatment expense to the nation's healthcare costs (1). Microbial pathogens from tap water are a significant source of HAI (2). Chlorine dioxide (ClO2) (CD) is a chemical disinfectant used to treat public drinking water supplies, primarily by municipal drinking water utilities. On-site, systemic application of CD, a relatively recent practice, has proven uniquely effective for controlling waterborne pathogens in healthcare facilities (3).CD treatment of institutional water is covered by the same rules that apply to municipal drinking water treatment systems;Federal regulatory requirements include daily monitoring of CD and its by-product, chlorite ion (ClO2-) (CI) (4). In order to comply with regulations, water samples are collected manually from taps at specified locations and transported to a centralized location for chemical analysis. The overall objective of the project is an integrated, fully automated, hardened system (System) that can perform all monitoring, recordkeeping and reporting functions required by US government regulations covering CD treatment of domestic water supplies. Principle components of the System are: (1) automated water sampling &flow control, (2) analytics, and (3) data management. Water sampling &flow control will incorporate recent advancements in Flow Injection Analysis (FIA), a rigorous methodology characterized by automated handling of sample and reagent solutions with strict control of reaction conditions (5). Analytics will include a proprietary electrochemical device (EC Probe) that is enabled by the research team's seminal innovations in solid-phase electrolytes and sol-gel process technology. This Phase I SBIR proposal (Proposal) has three Specific Aims: (1) optimize the EC Probe and flow system for long-term use under intended conditions;(2) design, build and test an integrated, fully-automated System;and (3) develop performance data that will demonstrate the value of engineering and cost-effective production of a standardized, commercial system in future phases. PUBLIC HEALTH RELEVANCE: CDC estimates that over 1.7 million infections per year are acquired by patients while they are in US hospitals. These healthcare associated infections (HAI) many of them caused by microbial pathogens from tap water result in nearly 100,000 deaths, an estimated $30-40 billion in direct treatment costs alone. are a significant, documented source of HAI. Upon completion, of this project the developed system-enabled compliance services would allow US healthcare institutions to implement Chlorine Dioxide water treatment, thereby substantially eliminating an entire class of HAI and saving tens of thousands of lives and billions of dollars per year.